Which phrase best completes the diagram? A. Coniferous forests
B. Large river basins
C. Numerous straits
D. Narrow isthmuses

The correct answer is B. Large river basins.

Explanation:

South America is a continent characterized by the presence of very large river systems that cover most of its territory. Thus, among others, the Amazon and its tributaries can be found, which cover more than 7 million square kilometers of extension; the Parana basin, in the south of the continent, covering more than 1 million and a half square kilometers; and the Orinoco basin, in Venezuela and Colombia, which covers almost 1 million square kilometers.

Thus, it can be seen that most of the South American territory close to the Atlantic coasts is covered by river basins of enormous magnitude, and there are also other smaller basins.